Lookup Policy On Multiple Match

I have a requirement where I need to read from and a table and write to a Flat File. The flat file has 3 fields
EMP_NO, Phone_NO, More_phone_NOs

I am doing a lookup on a table to get more_phone_nos field. I am trying to use 'Lookup policy on multiple match' property as 'Return all values'. Once I get these multiple values I need to concatenate all the values into one string and plug it into the (3rd filed)More_phone_nos field. Also in this process I need to check if the phone_no(2nd filed) is present in the returned values from look up in the 3rd filed(more_phone_nos) and omit it. Then concatenate them accordingly.

A comment on the original post - that's not how the "return all values" option works. It is meant to be used when there are 'duplicates' in your lookup cache based on the condition used and means you want all of the records returned by the lookup. For example, you send in one value to the lookup and it matches three records. Rather then take the first or last or 'any' value, all three are returned one after the other - one record goes in, three come out.

This choice can only be made when the lookup is created as it changes it from passive to active.

Thanks for your reply. I am unsure about the ports you are referring to in the expression transformation. Did you mean that I need to create variable ports. If so can you please list down all the ports in the expression trans and the order they should be. Also the calculations of the respective ports. Your help is much appreciated. Thanks